Quote:
Originally Posted by Mutant
Quote me any serious book that adds one more rule to the standard.
Parentheses
Exponents
DM Division and Multiplication
AS Addition and Subtraction
Should it be
Parentheses
Exponents
MD Multiplication and Division (but Multiplication first if there is no * sign)
AS Addition and Subtraction
???
AB means and will always mean just one thing: A*B

There is another rule that is not connected to PEMDAS but does effect it, they mention both rules in high school but for whatever reason never tell you that they are interconnected. That only happens in high school when they are cramming calculus down your throat.
Like I have said many times so far you HAVE to simply expressions, this was something you should have learned very well in any basic algebra class around the same time you learned PEMDAS. Simplifying expressions always comes before you can do anything else. The P in PEMDAS means that you have to simply what is in the parenthesis, simplify means, get rid of the parenthesis entirely before you continue on and in our given equation the step to get rid of the parenthesis looks something like this:
= 48/2(9+3)
= 48/2(12)
= 48/24
= 2
Quote:
Originally Posted by JeffTD
AB means A*B, but A(B) means (A*B).
The "2" in the original equation is not a value unto itself, it's just a quantity of (9+3). That's it. You don't divide 48 by 2, you divide it by two QUANTITIES of (9+3).

exactly, you can use a quantity of an expression to divide another number because that would mean you would go from having 2 quantities of 9+3 to 12 quantities of 9+3